It is desirous to reduce the noise generated by aircraft, for example, to lessen disruption or inconvenience, resulting from aircraft noise, caused to the public on the ground near airports. A significant amount of noise is generated by the interaction of the aircraft and the air flowing past it, which results in turbulent flows and consequently noise. It is particularly important to reduce noise created during approach of the aircraft on landing. During approach, a significant contribution to the amount of noise that the aircraft generates is made by the landing gear, which is typically deployed early for landing for safety reasons. The deployment of the landing gear increases drag and assists deceleration of the aircraft. During take-off, noise from the landing gear is a less significant factor because engine noise is generally greater and because the landing gear is generally stowed at the earliest opportunity to reduce drag and aid take-off. During normal flight, the landing gear of an aircraft is typically stowed in a landing gear bay, the bay being closed off by doors so that no part of the landing gear is subjected to the airflow.
WO01/04003 describes an aircraft landing gear and apparatus including a plurality of attachments for noise reduction purposes. One such attachment is shown in FIG. 1a, which shows both a plan view and a sectional view of a I-profile torque link 114 with a fairing attachment 116 bolted thereto. The attachment 116 is bolted into position using bolts 137, 138, which pass through the attachment 116 and an accompanying backing plate 139 placed behind the aperture 140 in the torque link 114. Edges 141, 142 defining the aperture 140 are therefore covered by the attachment 116, just as are edges 143, 144. The attachment 116 is a generally domed shape and is shaped to fill completely the aperture 114. The attachment 116 is therefore relatively bulky and needs to be formed of very lightweight material in order not to add significant weight to the landing gear assembly. Very lightweight material is prone to damage and would not, without additional protection, be fitted to the aircraft as a lifetime component. The attachment may need renewing routinely during service. Also, the attachment is attached using standard nuts and bolts, resulting in a fixing arrangement that is not able to be quickly dismantled.
US 2009/0176078 describes a noise-reduction method on an aircraft landing gear when the aircraft is flying and the undercarriage is deployed. The noise that would otherwise be caused by a noise-generating void of a structural element that forms part of the undercarriage is reduced. The method includes coating at least a portion of the structural element in a material that is of lower density than the material of the structural element in order to give the portion an aerodynamically smoother shape. The material completely surrounds at least part of the element and fills completely the noise-generating void of the structural element. The low density material is strengthened and protected by means of a composite material skin. The coating appears not to be removable from the structural element. Visual inspection of the structural element is not therefore easily permitted.
U.S. Pat. No. 6,048,477 discloses an aircraft landing gear component that protects the landing gear leg from debris and acts as a noise reduction fairing. As a result of the dual function of this component, its design is not driven solely by the desire to reduce noise whilst keeping weight and excessive structure to a minimum. The need to enable the component to function as a debris protection device needs also to be considered, which may compromise the design of the component insofar as its noise-reducing function is concerned.
WO 2004/089744 discloses a flexible annular sealing element that fits in the gap between an aircraft wheel tyre and the wheel rim on which the tyre is mounted. The disclosure of WO 2004/089744 provides no guidance on how to reduce noise on parts of the landing gear other than the wheel.
The present invention seeks to mitigate the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide an improved aircraft landing gear noise reduction assembly.